The movie collapses in a heap of self-defeat the moment it hits the screen with a modified Dragnet disclaimer that goes something like: “The story you are about to hear is true, only the names have been changed … etc …”

This is followed by “but the musical numbers remain entirely unchanged.”

Within seconds, we’re watching groups of campers pour from buses in perfect harmony. But they aren’t arriving at just any old camp in the woods. They’re treading the boards and belting Kumbaya at acting camp. Can you imagine?

Dozens upon dozens of privileged, outgoing and thoroughly extroverted little performers just waiting for their close-up in addition to the last piece of apple crumble: It’s the perfect setup for a horror movie.

And, yes, it’s also a musical, but make no mistake. Jerome Sable’s Stage Fright is not quite a stageworthy production in the bulging vein of Little Shop of Horrors or Witches or The Rocky Horror Picture Show.

Stage Fright

And no matter how hard it’s trying to be a satirical high-school production of Phantom of the Opera, it’s trying to accommodate too much horror cliché in its execution, and too many winking musical allusions in the script, to really succeed as anything.

At times, this movie starring Rocky Horror alum Meat Loaf offers a good bite of goofiness. Sometimes, it’s even on purpose. But there’s a sense of sanitized vulgarity that makes the whole thing feel off-kilter.

It’s like someone trying to tell a dirty joke using the word “pipi.” It’s quaint, but betrays the actual content and confuses the desired expression.

Sable is basing his whole film on two central ideas: Slasher teen horror and that droning Andrew Lloyd Webber musical with the mask.

It’s not a bad idea. But both forms demand complete and utter sincerity. Just like the kids trying to find their stride on stage, you have to be real in the moment to work the magic.

And while every performer we see gives his or her all, whether it’s Meat Loaf or Minnie Driver (poor dear), Sable’s direction isn’t on their wing.

The director abandons his stars to bring sarcastic distance to the subject matter. He wants to be funny because it would seem a musical-horror demands some wit, but when killing people forms a big chunk of your comic plot, you need a sense of opera.

Stage Fright gives it a few strangled yelps, but can’t pull off the great breath of wind — or the great dramatic range — required for its Wagnerian dreams to come true.